Sodium dihydrogen phosphate, with the chemical formula NaH₂PO₄, is an inorganic compound, commonly found in the form of anhydrous and dihydrate (NaH₂PO₄·2H₂O).
Basic properties：
- Appearance: white crystals or powder, easily soluble in water, the aqueous solution is weakly acidic.
- Solubility: easily soluble in water, insoluble in ethanol.
- pH value: The pH of 1% aqueous solution is about 4.5.
Main application：
- Food industry: used as acidity regulator, buffer, emulsifier, etc., for beverages, dairy products, etc.
- Medical field: used as buffer and laxative ingredients.
- Water treatment: used as corrosion inhibitor and water softener to prevent boiler scale.
- Laboratory: commonly used reagent for buffer solution preparation and chemical analysis.
- Others: also used in textile, papermaking, detergent and other industries.
Preparation method：
It is mainly produced by the reaction of phosphoric acid with sodium hydroxide or sodium carbonate. The reaction is as follows:
- H₃PO₄ + NaOH → NaH₂PO₄ + H₂O
- H₃PO₄ + 0.5Na₂CO₃ → NaH₂PO₄ + 0.5CO₂ + 0.5H₂O
Safety precautions：
- Inhalation: May irritate the respiratory tract, so please operate in a well-ventilated place.
- Contact: May irritate the skin and eyes, so please wear protective equipment when operating.
- Ingestion: Ingestion of large amounts may cause gastrointestinal discomfort, so please avoid accidental ingestion.
Storage：
It should be stored in a cool, dry, ventilated place, away from alkalis and flammable materials.
Summary：
Sodium dihydrogen phosphate is widely used in food, medicine, water treatment and other fields. When using it, attention should be paid to safe operation and storage conditions.